The present disclosure is directed to high side solenoid switch controls, and particularly to an overcurrent limiting circuit for the same.
Solenoids for use in engine systems are typically controlled using a high side solenoid switch. The high side solenoid switch is a transistor and is controlled using both software controls and hardware controls. Operation of the solenoid is controlled by the current passed through the high side solenoid switch. In order to protect the solenoid control hardware from overcurrents, a fault sensor is included within the hardware controls of the high side solenoid switch.
Typical fault sensors determine that a fault is present when a predefined overcurrent threshold is exceeded for greater than a set period of time. Determining that a fault condition is present only after an overcurrent has existed for greater than the set period of time is referred to as validating the overcurrent condition. Validating an overcurrent condition prevents a power source from being disconnected from the solenoid in the case of isolated transient occurrences. As a consequence of the overcurrent validation, excess current is allowed to flow from the power source during the overcurrent validation period.